Zero the Newton shape margin for ANYmal-D physX-Newton sim2sim

CONTRIBUTORS.md

@@ -97,6 +97,7 @@ Guidelines for modifications:
 * Grzegorz Malczyk
 * Haoran Zhou
 * Harsh Patel
+* Henry Hu
 * HoJin Jeon
 * Hongwei Xiong
 * Hongyu Li

source/isaaclab_tasks/changelog.d/henry-anymald-newton-margin.rst

@@ -0,0 +1,7 @@
+Fixed
+^^^^^
+
+* Fixed ANYmal-D rough-terrain locomotion terminating on spurious base contacts under the
+  Newton MJWarp backend by setting the Newton shape margin to zero in
+  :class:`~isaaclab_tasks.core.velocity.config.anymal_d.rough_env_cfg.AnymalDRoughEnvCfg`.
+  Other robots keep the shared default.

source/isaaclab_tasks/isaaclab_tasks/core/velocity/config/anymal_d/rough_env_cfg.py

@@ -21,3 +21,10 @@ def __post_init__(self):
         super().__post_init__()
         # switch robot to anymal-d
         self.scene.robot = ANYMAL_D_CFG.replace(prim_path="{ENV_REGEX_NS}/Robot")
+
+        # ANYmal-D's base capsule passes within a few millimetres of the thigh colliders, so
+        # the shared 1 cm Newton shape margin inflates them into constant overlap and trips
+        # the base_contact termination. Other robots keep the default.
+        newton_cfg = getattr(self.sim.physics, "newton_mjwarp", None)
+        if newton_cfg is not None:
+            newton_cfg.default_shape_cfg = newton_cfg.default_shape_cfg.replace(margin=0.0)